This is my Atari Atarians Pinball. You'd think it was brand new as the playfield has two very small wear spots near the kicker holes - not a machine made in 1976. This machine is I would NOT recommend this machine for anyone not intimately familiar with electronics or pinball repair due to the large number of design issues and lack of parts.
The first thing striking about the machine is it's size - it's a wide body which I don't think ever caught on. You very rarely saw these Atari pinballs on location due to maintenance issues and that fact that they had minimal play appeal. I suppose that's why this one, and I've heard most of them, look like new. There are a few scuffs on the side from sitting broken in a garage for years.
The upside of all this is that the machine has a number of features never seen in other pinballs. In fact Atari themselves discontinued some features of this machine immediately such as the magnetic switches. Although they work flawlessly I understand the issue was that players could run a magnet near the machine and rack up high scores. Who'd of thunk...
I bought this machine not because I particularly like it but rather the challenge to restore it. Much fun!
Lower playfield. See the 'stars' - those are the locations of the magnetic ball sensors mounted under the board. They actually work very well and would have been a real pinball innovation had they not had a flaw - players could score points by swiping magnets over them - back to the drawing board. As far as I know 'Atarians' in the only pinball to ever use magnetic sensors. Also note the four flippers ala Gottlieb's 'King Kool' -- these are treacherous and it's very easy to lose your ball between them.
This is one of the hardest games I've ever played. Simple - you have to light the numbers 1-9 to light the special - the targets 3 and 8 , however, are very difficult to hit.
The game has a coin door lockout switch - the same switch found on Atari video game back doors. On a pinball this is a pain in the as everytime you open it the game shuts off. Well, that got relocated very quickly :)
Basically the board is very simply - an mc6800 cpu with simply address decoding, ram, and rom. actual communication with the world is performed via a separate TTL logic counter system which takes over the CPU bus at intervals. Odd but it works.
The symptom was that the game would come on, partial display or all 8's. All address, data, and signals were ok. The 'switch read' strobe was not strobbing. The watchdog timer was not tripping so I made the assumption that the cpu was simply waiting in some loop for some ram data that would never change. I have no ram tester for verification so I ordered a quantity of 4 of the 2111 sram chips from JAMECO. Fortunately I ordered 6 ( I needed 4 ). These arrived and fixed the problem. This board has 8 four bit rom chips. I hope they hold up.
Some lamp driver uln2003's and connectors were intermittent. Generally this is easy to fix but due to the size of the cabinet you have to perform acrobatics to monitor the board and adjust the connectors. It wouldn't be pinball without it!
Of special interest is the use of rotary solenoids. The company (LEDEX) who made this is still around. Actually these are very nice and quiet solenoids, not the 'clunk' of a traditional solenoid. When I got the machine, for some reason, someone had replaced a few of the 2 amp slo blo solenoid fuses with 30 amp fuses. Needless to say this MELTED 2 of the rotary solenoids and the drive transistors. Crap - where to find solenoids. A quick look online left me thwarted. I was hoping to find some $10 solenoids somewhere. I'm sure someone has some but I've not found them. So I did the next best thing - rewrap the coils.
It's fairly easy to re-wrap a standard pinball coil as all you have is a bobbin and wire. Marvin's Marvelous Mechanical Museum has a great page on rewinding coils here. These rotary solenoids, however, have a machine pressed housing and if the bobbin swells, from burning wire, you'll have to re-shape it a little to accommodate the permanent magnet on the armature. Here's my photos of the project. There are different end mounting for the armature ( some e-clip, some peened ) so the procedure will be a little different for each. The basic premise is you must remove the armature (making sure not to loose the 3 little balls), cracked the case, remove and re-wrap the coil, re-assemble. So, here's the pics ...
The solenoid with peened end.
Drilling out the peen.
Popping out the armature - caution: three little balls will pop out.
The three balls
Popping off the solenoid housing. The case is 'pressed' on and will take a great deal of coercion to remove it. Here I'm sticking big flat head screwdriver under the round opening and prying.
The coil in the removed housing.
The coil - burned pretty bad - there's a hole in the wall which needs covering to prevent the new wire from touching the moving armature.
The big burned hole. Removing the wire from this core is a chore. It took about 30 minutes as the wire all melted together and to the bobbin walls.
Winding the bobbin with new wire in the drill press. Note- the big hole above was covered with a thin piece of plastic from some blister card packaging. For wire I used a relay from my junk box with a 'close enough' diameter. Note: This was not a great idea since the diameter was slightly larger than the original coil wire. To compound this the bobbin was burned and warped. I wrapped the wire with a drill press which means sloppy,loose windings. This leads to shorter wire length which means lower coil nominal impedance. The coil is 20 ohms from the factory, 8 ohms after my repair. This causes additional load on the driver. I had to add a heat sink to the drive transistor. In any case it all works now.
The new coil - wrapped with electrical tap being inserted in the housing. Note the plastic spacer to prevent shorting.
Re-pressing the housing together in a vice.
Those darn balls again - make sure you orient the armature correctly as you'll only get one chance to install it. Prior to peening put the armature in the solenoid housing a make sure it moves easily. You may need to push on the coil bobbin as portions may touch the magnet on the armature. The bobbin most likely swelled a little when the coil burned - just enough to cause grief.
Re-pressing the armature. Note the 1/4" nut to allow targeted pressing. HOPEFULLY the assembly will hold. If is doesn't ( test by trying to pop the washer with a screwdriver) then you'll have to get a REALLY SMALL drill and tap to put a screw in. I would have done this but didn't have a small enough tap.
The completed solenoid.